FLUKE 731B, DC Reference Standard, Repair [success]

[HighVoltage]

And here are the comparisons of the 4 different 34401A meters
Same setup, just different days

From the previous 3458A data we know, that all four 731B standards are stable within 1/2 PPM during the measurements.
So, the changes in these graphs are based on variations in each of the four 34401A

There is a good correlation for each 34401A from day to day
What surprises me the most is the differences between the four different 34401A meters
I would have expected each one to behave about the same.

I have definitely reached the limits of the 34401A meters with this little test.
 

[ManateeMafia]

It looks like you have yourself a nice collection of references going. Do you have any plans on monitoring these with a scanner and nanovoltmeter?
I have several 10v refs that get scanned daily and it helps to see the stability without spending a lot of time measuring them by hand.

I don't remember seeing you with a nanovoltmeter so maybe that is on your list of future teardown/repairs?

[HighVoltage]

It looks like you have yourself a nice collection of references going. Do you have any plans on monitoring these with a scanner and nanovoltmeter?
I have several 10v refs that get scanned daily and it helps to see the stability without spending a lot of time measuring them by hand.

I don't remember seeing you with a nanovoltmeter so maybe that is on your list of future teardown/repairs?

ManateeMafia
What nanovoltmeter and scanner are you using?

I have been looking for a broken Agilent 34420A for a long time but no luck so far and in working condition, they are just far too expensive.
Unfortunately, Keysight will stop selling the 34420A in Europe by the end of 2016 and most likely the price for a used one will even climb up.

Hmm, .... may be I should get a new one with a good discount, if they have any left in the last week of December.
I would be very much interested to get to know your scanning setup

[ManateeMafia]

I am using a Data Proof 160A and a 34420A that I got from eBay. The Keithley 2182(A) is also a good meter as is the Keithley 182.

The software is Windows based and runs on a nano-itx headless PC which scans and saves the results to a Postgresql database. A lot more work is needed to generate plots of the results. There will be a separate program to act as a web server generating plots and reports for a remote connection . A BME280 + RPi is used as a Fluke 1620A and is queried over the network for the environmental data.

This has turned into a much bigger project than I planned.

[plesa]

I have been looking for a broken Agilent 34420A for a long time but no luck so far and in working condition, they are just far too expensive.
Unfortunately, Keysight will stop selling the 34420A in Europe by the end of 2016 and most likely the price for a used one will even climb up.

What about this one?
http://www.ebay.com/itm/HP-34420A-NanoVolt-MicroOhm-Meter-/112213078051?
BTW nice collection of references. When hooked 3458A to references I was impressed like you by it stability and noise level.

[Theboel]

Hi High Voltage and Every one,

When We measure the Fluke 731B against 34401 we can say it like compare LM399 with SZA263 off course with some uncertainty and when we compare 731B with 3458A are like to compare SZA263 with LTZ1000 again with some uncertainty.

When I see the high voltage report I believe I can say SZA263 are better than LM399 and comparable with LTZ1000, are my conclusion is wrong ?
 

[HighVoltage]

I agree so far that the SZA263 is about as stable as the LTZ1000.

But keep in mind, that the LTZ1000 is heated and the SZA263 is not.
I think when I start to take measurements over temperature, we will see much larger differences between the two.
 

[Theboel]

I agree so far that the SZA263 is about as stable as the LTZ1000.

But keep in mind, that the LTZ1000 is heated and the SZA263 is not.
I think when I start to take measurements over temperature, we will see much larger differences between the two.

My conclusion based from the same ambient temperature for 731B and 3458A but who know where is the sweet spot of SZA263 and according to story about motorola stop to made SZA263 because lack of demand I think its very hard to prove which one is really "the king" except some day a "hardcore volt nut" do face to face experiment 
for now I declare I want 731B for my birthday present     

[HighVoltage]

Well, they are not too expensive and available, so your wish should not be so hard to realize.
I was also looking for a 732B but that will probably stay a wish for a long long time, I think.

You might be right in the comparison.
I will continue my measurements for sure.